This article presents an accident that took place at a Petrobras Transporte S.A. - TRANSPETRO pipeline right-of-way (ROW), involving one of its pipes: ORSUB (Southern Bahia diesel, gasoline and LPG 360km Φ10/Φ8 pipeline). Basically, the mentioned occurrence shows the influence of collapses in third-party constructions in TRANSPETRO facilities’ integrity. The event in Bahia consisted in the exposure of 70m of the pipeline, caused by a dam breach from a private property nearby. Due to the failure, the water from the reservoir streamed through the terrain, dragging and destroying whatever it came across (small houses wrecks, torn trees and crops were found along the water track), reaching the pipeline ROW around 700m from its origin, in a narrow rocky valley, hence gaining power and speed, and swept away the soil that covered the pipe, provoking a 70m long, 2m deep and 5m across opening. The fact that the water ran along the pipe and did not hit it perpendicularly led to minor damages. The consequences, whether it happened otherwise, would be much more serious, especially in an environmental way, as this happened within the limits of a cocoa and banana farm, with a creek not even 10m away. A number of irregularities were found in the dam wreck, such as under dimensioned valve and intake structure and the lack of a spillway were the main reasons that caused the breach. Major events like this bring to attention the fact that some farmers build their own dams (within the limits of their properties) with no expertise on the matter whatsoever and often without any professional assistance. This represents a tremendous jeopardy for almost everything existing downstream the dam, such as crops, cattle, houses and people. After the dam rupture, the geotechnical engineers from TRANSPETRO started a study which mapped 35 dams only in ORSUB ROW neighbourhood, at least 3 of them were classified as critical. A hydrodynamic simulation, based on the accident described here, is being developed, so the engineers can predict what might happen to the pipeline ROW and, in a worst case scenario, to the pipe itself, whether another dam failure occurs.

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